Swarming Aqua Sperm Micromotors for Active Bacterial Biofilms Removal in Confined Spaces.

Microscale self-propelled robots show great promise in the biomedical field and are the focus of many researchers. These tiny devices, which move and navigate by themselves, are typically based on inorganic microstructures that are not biodegradable and potentially toxic, often using toxic fuels or elaborate external energy sources, which limits their real-world applications. One potential solution to these issues is to go back to nature. Here, the authors use high-speed Aqua Sperm micromotors obtained from North African catfish (Clarias gariepinus, B. 1822) to destroy bacterial biofilm. These Aqua Sperm micromotors use water-induced dynein ATPase catalyzed adenosine triphosphate (ATP) degradation as biocompatible fuel to trigger their fast speed and snake-like undulatory locomotion that facilitate biofilm destruction in less than one minute. This efficient biofilm destruction is due to the ultra-fast velocity as well as the head size of Aqua Sperm micromotors being similar to bacteria, which facilitates their entry to and navigation within the biofilm matrix. In addition, the authors demonstrate the real-world application of Aqua Sperm micromotors by destroying biofilms that had colonized medical and laboratory tubing. The implemented system extends the biomedical application of Aqua Sperm micromotors to include hybrid robots for fertilization or cargo tasks.

Exploration of small RNA biomarkers for testicular injury in the serum exosomes of rats.

Testicular injury is often observed in drug development. Serum hormones are usually used as noninvasive biomarkers for testicular injury; however, their sensitivities are low. Therefore, it is difficult to monitor testicular injury in drug development. In recent years, molecules in body fluid exosomes have attracted attention as biomarkers for diseases. In this study, small RNAs in serum exosomes were analyzed to identify noninvasive biomarkers of testicular injury in rats, which are often used in preclinical drug development. The rat models of testicular injury were prepared by a single oral administration of 2000 mg/kg ethylene glycol monomethyl ether, in which spermatocyte degeneration and Sertoli cell vacuolation were observed, or 400 mg/kg carbendazim, in which Sertoli cell vacuolation and seminiferous tubule dilation were observed. Serum exosomal small RNA-seq analysis of these models was performed. The analysis identified 3 small RNAs that fluctuated in common between the models, and miR-423-5p and miR-128-3p were selected as candidate markers. For evaluating these candidate markers in other testicular injury models, the models were prepared by a single oral administration of 60 mg/kg 1,3-dinitrobenzene or 500 mg/kg nitrofurazone, and spermatocyte degeneration and Sertoli cell vacuolation were observed. In qPCR analysis, these exosomal miRNAs were upregulated in all models except for the 1,3-dinitrobenzene model, in which severe hemolysis was observed. By contrast, these miRNAs in whole serum extracts did not significantly change in any of the models. In conclusion, we identified miR-423-5p and miR-128-3p in serum exosomes as noninvasive biomarkers for testicular injury in rats.

qRT-PCR versus IFA-based Quantification of Male and Female Gametocytes in Low-Density Plasmodium falciparum Infections and Their Relevance for Transmission.

BACKGROUND: Accurate quantification of female and male gametocytes and sex ratios in asymptomatic low-density malaria infections are important for assessing their transmission potential. Gametocytes often escape detection even by molecular methods, therefore ultralow gametocyte densities were quantified in large blood volumes. METHODS: Female and male gametocytes were quantified in 161 PCR-positive Plasmodium falciparum infections from a cross-sectional survey in Papua New Guinea. Ten-fold concentrated RNA from 800 µL blood was analyzed using female-specific pfs25 and male-specific pfmget or mssp qRT-PCR. Gametocyte sex ratios from qRT-PCR were compared with those from immunofluorescence assays (IFA). RESULTS: Gametocytes were identified in 58% (93/161) P. falciparum-positive individuals. Mean gametocyte densities were frequently below 1 female and 1 male gametocyte/µL by qRT-PCR. The mean proportion of males was 0.39 (95% confidence interval, 0.33-0.44) by pfs25/pfmget qRT-PCR; this correlated well with IFA results (Pearsons r2 = 0.91; P < .001). A Poisson model fitted to our data predicted 16% P. falciparum-positive individuals that are likely to transmit, assuming at least 1 female and 1 male gametocyte per 2.5 µL mosquito bloodmeal. CONCLUSIONS: Based on model estimates of female and male gametocytes per 2.5 µL blood, P. falciparum-positive individuals detected exclusively by ultrasensitive diagnostics are negligible for human-to-mosquito transmission.Estimating the transmission potential of ultralow-density malaria infections informs interventions. Almost all infections with ≥1 female and male gametocyte per 2.5 µL mosquito bloodmeal, and thus with highest likelihood of contributing to human-to-mosquito transmission, were detectable by standard molecular diagnostics.

Isolation and Analysis of the CGG-Repeat Size in Male and Female Gametes from a Fragile X Mouse Model.

Analysis of individual gametes has a number of applications in the study of the mechanism of repeat expansion in mouse models of the fragile X-related disorders, as well as in mouse models of other repeat expansion diseases. This chapter describes the techniques required to isolate oocytes and male gametes of different stages of maturity, along with the techniques required to accurately determine the repeat number in these gametes.

Differential localization of histone variant TH2B during the first round compared with subsequent rounds of spermatogenesis.

BACKGROUND: Male germ cells are unique because they express a substantial number of variants of the general DNA binding proteins, known as histones, yet the biological significance of these variants is still unknown. In the present study, we aimed to address the expression pattern of the testis-specific histone H2B variant (TH2B) and the testis-specific histone H2A variant (TH2A) within the neonatal mouse testis. RESULTS: We demonstrate that TH2B and TH2A are present in a testis-enriched for undifferentiated spermatogonia. Co-localization studies with an undifferentiated marker, ZBTB16, revealed that TH2B and ZBTB16 co-localize in the neonatal testis. Upon the appearance of the primary spermatocytes, TH2B no longer co-localized with the ZBTB16 positive spermatogonia but were instead detected within the differentiating spermatogonia. This pattern of expression where TH2B and ZBTB16 no longer co-localize was maintained in the adult testis. CONCLUSION: These findings are in contrast to previous studies, which demonstrated that TH2B and TH2A were found only in adult spermatocytes. Our data are in support of a switch in the expression of these variants following the first round of spermatogonial differentiation. These studies reinforce current understandings that spermatogonia within the neonatal mouse testis are inherently different from those residing within the adult testis.

REC114 Partner ANKRD31 Controls Number, Timing, and Location of Meiotic DNA Breaks.

Double-strand breaks (DSBs) initiate the homologous recombination that is crucial for meiotic chromosome pairing and segregation. Here, we unveil mouse ANKRD31 as a lynchpin governing multiple aspects of DSB formation. Spermatocytes lacking ANKRD31 have altered DSB locations and fail to target DSBs to the pseudoautosomal regions (PARs) of sex chromosomes. They also have delayed and/or fewer recombination sites but, paradoxically, more DSBs, suggesting DSB dysregulation. Unrepaired DSBs and pairing failures-stochastic on autosomes, nearly absolute on X and Y-cause meiotic arrest and sterility in males. Ankrd31-deficient females have reduced oocyte reserves. A crystal structure defines a pleckstrin homology (PH) domain in REC114 and its direct intermolecular contacts with ANKRD31. In vivo, ANKRD31 stabilizes REC114 association with the PAR and elsewhere. Our findings inform a model in which ANKRD31 is a scaffold anchoring REC114 and other factors to specific genomic locations, thereby regulating DSB formation.

Protein expression of the transcription factors DMRT1, TCLF5, and OCT4 in selected germ cell neoplasms of the testis.

In the present study, we investigated protein expression of the transcription factors mammalian doublesex and mab-3 related transcription factor 1 (DMRT1), basic helix-loop-helix transcription factor-like 5 (TCLF5), and octamer-binding transcription factor 4 (OCT4) in normal human spermatogenesis, testicular mixed germ cell-sex cord stromal tumor (MGC-SCST), spermatocytic tumor, and seminoma. In normal human spermatogenesis, DMRT1 is expressed in the nuclei of spermatogonia but not in those of more mature germ cells. By way of contrast, TCLF5 is expressed in the nuclei of some clusters of primary spermatocytes that have entered meiosis 1, in secondary spermatocytes, and in round (early) spermatids in the seminiferous tubules of adults during the reproductive years. OCT4 is expressed in primordial germ cells but not in the seminiferous tubules of the normal adult testis during the reproductive years. DMRT1 is expressed in the germ cells of both testicular MGC-SCST and spermatocytic tumor, whereas TCLF5 is not expressed in either neoplasm. These low-grade neoplasms, however, differ histologically in that all the germ cell nuclei of testicular MGC-SCST resemble spermatogonia, whereas in spermatocytic tumor, the nuclei of the medium-sized and large cells resemble those of primary spermatocytes. Both neoplasms lack expression of OCT4. By way of contrast, in seminoma, a fully malignant testicular germ cell tumor, the germ cell nuclei express OCT4 but do not express either DMRT1 or TCLF5.

Cell-Like Micromotors.

In the past decade, versatile micro- and nanosized machines have emerged as active agents for large-scale detoxification, sensing, microfabrication, and many other promising applications. Micromachines have also been envisioned as the next advancement in dynamic therapy with numerous proof-of-concept studies in drug delivery, microsurgery, and detoxification. However, the practical use of synthetic micromotors in the body requires the development of fully biocompatible designs facilitating micromotor movement in biological fluids of diverse composition and displaying desired functions in specific locations. The combination of the efficient movement of synthetic micromotors with the biological functions of natural cells has resulted in cell-like micromotors with expanded therapeutic and toxin-removing capabilities toward different biological applications. Thus, these biocompatible and biomimetic cell-like micromotors can provide efficient movement in complex biofluids and mimic the functionalities of natural cells. This Account highlights a variety of recent proof-of-concept examples of cell-like micromotors, based on different designs and actuation mechanisms, which perform diverse in vivo tasks. The cell-like micromotors are divided into two groups: (i) cell membrane-coated micromotors, which use natural cell membranes derived from red blood cells, platelets, or a combination of different cells to cloak and functionalize synthetic motors, and (ii) cell-based micromotors, which directly use entire cells such as blood cells, spermatozoa, and bacteria as the micromotor engine. Cell-like micromotors, composed of different cellular components and actuated by different mechanisms, have shown unique advantages for operation in complex biofluids such as blood. Due to the inherent biocompatibility of cell-derived materials, these cell-like micromotors do not provoke an immune response while utilizing useful secondary functions of the blood cells such as strong ability to soak up foreign agents or bind toxins. Additionally, the utilization of autonomously motile cells (e.g., bacteria) allows for built-in chemotactic motion, which eliminates the need for harmful fuels or complex actuation equipment. Furthermore, a broad range of cells, both passive and motile, can be incorporated into micromachine designs constituting a large library of functional components depending on the limits of the desired application. The coupling of cellular and artificial components has led to active biohybrid swimming microsystems with greatly enhanced capabilities and functionalities compared to the individual biological or synthetic components. These characteristics have positioned these cell-like micromotors as promising biomimetic dynamic tools for potential actuation in vivo. Finally, the key challenges and limitations of cell-like micromotors are discussed in the context of expanded future clinical uses and translation to human trials.

Transient reduction of DNA methylation at the onset of meiosis in male mice.

BACKGROUND: Meiosis is a specialized germ cell cycle that generates haploid gametes. In the initial stage of meiosis, meiotic prophase I (MPI), homologous chromosomes pair and recombine. Extensive changes in chromatin in MPI raise an important question concerning the contribution of epigenetic mechanisms such as DNA methylation to meiosis. Interestingly, previous studies concluded that in male mice, genome-wide DNA methylation patters are set in place prior to meiosis and remain constant subsequently. However, no prior studies examined DNA methylation during MPI in a systematic manner necessitating its further investigation. RESULTS: In this study, we used genome-wide bisulfite sequencing to determine DNA methylation of adult mouse spermatocytes at all MPI substages, spermatogonia and haploid sperm. This analysis uncovered transient reduction of DNA methylation (TRDM) of spermatocyte genomes. The genome-wide scope of TRDM, its onset in the meiotic S phase and presence of hemimethylated DNA in MPI are all consistent with a DNA replication-dependent DNA demethylation. Following DNA replication, spermatocytes regain DNA methylation gradually but unevenly, suggesting that key MPI events occur in the context of hemimethylated genome. TRDM also uncovers the prior deficit of DNA methylation of LINE-1 retrotransposons in spermatogonia resulting in their full demethylation during TRDM and likely contributing to the observed mRNA and protein expression of some LINE-1 elements in early MPI. CONCLUSIONS: Our results suggest that contrary to the prevailing view, chromosomes exhibit dynamic changes in DNA methylation in MPI. We propose that TRDM facilitates meiotic prophase processes and gamete quality control.

Hexavalents in spermatocytes of Robertsonian heterozygotes between Mus m. domesticus 2n=26 from the Vulcano and Lipari Islands (Aeolian Archipelago, Italy).

The size and shape of the chromosomes, as well as the chromosomal domains that compose them, are determinants in the distribution and interaction between the bivalents within the nucleus of spermatocytes in prophase I of meiosis. Thus the nuclear architecture characteristic of the karyotype of a species can be modified by chromosomal changes such as Rb chromosomes. In this study we analysed the meiotic prophase nuclear organization of the heterozygous spermatocytes from Mus musculus domesticus 2n=26, and the synaptic configuration of the hexavalent formed by the dependent Rb chromosomes Rbs 6.16, 16.10, 10.15, 15.17 and the telocentric chromosomes 6 and 17. Spreads of 88 pachytene spermatocytes from two males were studied and in all of them five metacentric bivalents, four telocentric bivalents, one hexavalent and the XY bivalent were observed. About 48% of the hexavalents formed a chain or a ring of synapsed chromosomes, the latter closed by synapsis between the short arms of telocentric chromosomes 6 and 17.  About 52% of hexavalents formed an open chain of 10 synapsed chromosomal arms belonging to 6 chromosomes.  In about half of the unsynapsed hexavalents one of the telocentric chromosome short arms appears associated with the X chromosome single axis, which was otherwise normally paired with the Y chromosome.  The cluster of pericentromeric heterochromatin mostly determines the hexavalent's nuclear configuration, dragging the centromeric regions and all the chromosomes towards the nuclear envelope similar to an association of five telocentric bivalents. These reiterated encounters between these chromosomes restrict the interactions with other chromosomal domains and might favour eventual rearrangements within the metacentric, telocentric or hexavalent chromosome subsets. The unsynapsed short arms of telocentric chromosomes frequently bound to the single axis of the X chromosome could further complicate the already complex segregation of hexavalent chromosomes.

Preparation of Meiotic Chromosome Spreads from Mouse Spermatocytes.

Mammalian meiosis is a dynamic developmental process that occurs in germ cells and can be studied and characterized. Using a method to spread nuclei on the surface of slides (rather than dropping them from a height), we demonstrate an optimized technique on mouse spermatocytes that was first described in 1997. This method is widely used in laboratories to study mammalian meiosis because it yields a plethora of high quality nuclei undergoing substages of prophase I. Seminiferous tubules are first placed in a hypotonic solution to swell spermatocytes. Then spermatocytes are released into a sucrose solution to create a cell suspension, and nuclei are spread onto fixative-soaked glass slides. Following immunostaining, a diversity of proteins germane to meiotic processes can be examined. For example, proteins of the synaptonemal complex, a tripartite structure that connects the chromosome axes/cores of homologs together can be easily visualized. Meiotic recombination proteins, which are involved in repair of DNA double-strand breaks by homologous recombination, can also be immunostained to evaluate progression of prophase I. Here we describe and demonstrate in detail a technique widely used to study mammalian meiosis in spermatocytes from juvenile or adult male mice.

Different expression of leptin and IGF1 in the adult and prepubertal testis in dogs.

Leptin (Lep) and insulin-like growth factor 1 (IGF1) are implicated in the regulation of testicular function, but in dogs, our knowledge is limited to the possible role of the IGF1 system in testicular tumours. In this study, we aimed to describe and compare gene expression and protein localization of Lep, IGF1 and their receptors (LepR and IGF1R, respectively) in the testis of healthy adult and prepubertal dogs. Testes were collected from sexually healthy mature (n = 7) and from 8-week-old dogs (n = 7). Relative gene expression of Lep, LepR, IGF1 and IGF1R was determined by semi-quantitative real-time (TaqMan) PCR and cellular distribution in the testis by immunohistochemistry. Statistical analysis was carried out with Student's t test. Lep and LepR mRNA concentration was similar between the two groups, but IGF1 and IGF1R gene expression was significantly higher in the 8-week-old pups. Protein localization and the intensity of signals differed by age. In adults, Lep and LepR immunoreactivity was detected in spermatocytes and spermatids. Leydig cells showed sporadic, weak Lep staining. In prepubertal animals, intense Lep signals were present in Leydig and Sertoli cells, and LepR was found in Leydig cells. IGF1 and IGF1R protein was expressed in spermatogonia of the mature testis; IGF1 signals in Leydig cells seemed stronger than IGF1R. In the pups, IGF1 and IGF1R staining was detected in Leydig cells and in gonocytes. Sertoli cells showed weak IGF1 and sporadic, weak IGF1R signals. In conclusion, Lep and IGF1 may support spermatogenesis in adult dogs and mediate Leydig cell function. In the immature testis, they may promote development of Sertoli and Leydig cells and gonocytes.

Ultrastructural immunogold localization of major sperm protein (MSP) in spermatogenic cells of the nematode Acrobeles complexus (Nematoda, Rhabditida).

The nematode spermatozoa represent a highly modified (aberrant) type of male gametes that lack a flagellum but for which the process of spermatogenesis culminates in the production of a crawling spermatozoon on the basis of the cytoskeletal component known as "major sperm protein", or MSP. MSP is also known as an important hormone triggering oocyte maturation and ovulation in the model nematode Caenorhabditis elegans, where this protein was first identified. However, direct evidence of MSP localization and of its fate in nematode spermatogenic cells is rare. In this study, the spermatogenesis and sperm structure in the rhabditid nematode Acrobeles complexus (Rhabditida: Tylenchina: Cephalobomorpha: Cephaloboidea: Cephalobidae) has been examined with electron microscopy. Morphological observations were followed by high-pressure freezing and freeze-substitution fixation which allows post-embedding immunogold localization of MSP in all stages of sperm development using antibodies raised for MSP of C. elegans. In spermatocytes, synthetic activity results in the development of specific cellular components, fibrous bodies (FB) and membranous organelles (MO), which appear as FB-MO complexes where the filamentous matter of FB has been MSP-labeled. The spermatids subdivide into a residual body with superfluous cytoplasm, and a main cell body which contains nucleus, mitochondria and FB-MO complexes. These complexes dissociate into individual components, MO and FB, with the MSP being localized in FB. Immature spermatozoa from testes are opaque cells where a centrally located nucleus is surrounded by mitochondria, MO and FB clustered together, the MSP still being localized only in FB. Cytoplasm of mature spermatozoa from spermatheca is segregated into external pseudopods lacking organelles and a central cluster of mitochondria with intact MO surrounding the central nucleus. The FB ultimately disappear, and the MSP labeling becomes concentrated in the filamentous content of pseudopods and cytoplasm of the main cell body. Although the spermatogenesis and sperm structure of A. complexus is similar to that of many other rhabditid nematodes, their intact MO makes the morphology of the mature spermatozoa distinct from the "rhabditid pattern" and may be considered as a synapomorphy. The MSP localization in spermatogenic cells of A. complexus also follows the "rhabditid pattern" described in C. elegans and Ascaris spp. Our results and techniques of MSP labeling of A. complexus spermatogeneous cells reveal new possibilities to elucidate different research questions on MSP localization in nematodes related to C. elegans. Furthermore, the laboratory-cultured A. complexus strains can be used as a new and fascinating model to study MO and MSP functions in nematode reproduction.

Expression of the oncoprotein gankyrin and phosphorylated retinoblastoma protein in human testis and testicular germ cell tumor.

OBJECTIVE: The oncoprotein, gankyrin, is known to facilitate cell proliferation through phosphorylation and degradation of retinoblastoma protein. In the present study, we evaluated the expression of gankyrin and phosphorylated retinoblastoma protein in human testis and testicular germ cell tumors. METHODS: The effects of suppression of gankyrin by locked nucleic acid on phosphorylation status of retinoblastoma and cell proliferation were analyzed using western blot analysis and testicular tumor cell line NEC8. The expressions of gankyrin, retinoblastoma and retinoblastoma protein were analyzed in 93 testicular germ cell tumor samples and five normal human testis by immunohistochemistry. The retinoblastoma protein expression was determined using an antibody to retinoblastoma protein, Ser795. RESULTS: Gankyrin was expressed in NEC8 cells as well as a normal human testis and testicular tumors. Suppression of gankyrin by locked nucleic acid led to suppression of retinoblastoma protein and cell proliferation in NEC8 cells. Immunohistochemistry of normal testis showed that gankyrin is expressed dominantly in spermatocytes. In testicular germ cell tumors, high expressions of gankyrin and phosphorylated-retinoblastoma protein were observed in seminoma and embryonal carcinoma, whereas the expressions of both proteins were weak in histological subtypes of non-seminoma. Growing teratoma and testicular malignant transformation tissues expressed phosphorylated-retinoblastoma protein strongly, but gankyrin faintly. CONCLUSION: Gankyrin is dominantly expressed in normal spermatocytes and seminoma/embryonal carcinoma, and its expression correlates well with retinoblastoma protein expression except in the growing teratoma and testicular malignant transformation cases. These data provide new insights into the molecular mechanisms of normal spermatogenesis and pathogenesis of testicular germ cell tumors.

Spermatocytic seminoma: a 21 years' retrospective study in a tertiary care hospital in Pakistan.

BACKGROUND: Spermatocytic seminoma is a rare testicular germ cell tumor of old men. Accounting for 1-4% of all seminomas, spermatocytic seminomas have distinct pathogenesis, histological features, immunohistochemical profile and comparatively benign clinical behavior which distinguishes them from other germ cell tumors, especially classic seminoma. AIMS: The purposes of our study were to assess the patient demographics, pathological features and to evaluate the utility of CD 117 immunostain along with other immunohistochemical stains in distinguishing Spermatocytic seminomas from classic seminomas. MATERIAL AND METHODS: All spermatocytic seminomas patients diagnosed during 1992 to 2013 at Section of Histopathology, Department of Pathology and Microbiology, Aga Khan University hospital were included. Patient characteristics, histological details and follow-up data of few patients were available. CD 117 expression was determined by immunohistochemistry. RESULTS: Total 16 cases of Spermatocytic seminomas were reviewed. Median age was 60 years and average tumor size was 10.4 cms. Microscopically, all of the 16 cases showed presence of edema and absence of lymphocytic infiltrate and intratubular germ cell neoplasia. Cytoplasmic glycogen was negative in all 13 cases, PLAP immunostain was negative in all 12 cases, while CD 117 was positive in all 8 cases, where applied. CONCLUSION: CD 117 is of limited utility in differentiating the spermatocytic seminoma from classic seminoma as it is expressed in significant number of spermatocytic seminomas. However, different histological features, PAS special stain and PLAP immunostain are significantly helpful in distinguishing these two entities.

Impaired function of the blood-testis barrier during aging is preceded by a decline in cell adhesion proteins and GTPases.

With increasing age comes many changes in the testis, including germ cell loss. Cell junctions in the testis tether both seminiferous epithelial and germ cells together and assist in the formation of the blood-testis barrier (BTB), which limits transport of biomolecules, ions and electrolytes from the basal to the adluminal compartment and protects post-meiotic germ cells. We hypothesize that as male rats age the proteins involved in forming the junctions decrease and that this alters the ability of the BTB to protect the germ cells. Pachytene spermatocytes were isolated from Brown Norway rat testes at 4 (young) and 18 (aged) months of age using STA-PUT velocity sedimentation technique. RNA was extracted and gene expression was assessed using Affymetrix rat 230 2.0 whole rat genome microarrays. Microarray data were confirmed by q-RT-PCR and protein expression by Western blotting. Of the genes that were significantly decreased by at least 1.5 fold, 70 were involved in cell adhesion; of these, at least 20 are known to be specifically involved in junction dynamics within the seminiferous epithelium. The mRNA and protein levels of Jam2, Ocln, cdh2 (N-cadherin), ctnna (α-catenin), and cldn11 (involved in adherens junctions), among others, were decreased by approximately 50% in aged spermatocytes. In addition, the GTPases Rac1 and cdc42, involved in the recruitment of cadherins to the adherens junctions, were similarly decreased. It is therefore not surprising that with lower expression of these proteins that the BTB becomes diminished with age. We saw, using a FITC tracer, a gradual collapse of the BTB between 18 and 24 months. This provides the opportunity for harmful substances and immune cells to cross the BTB and cause the disruption of spermatogenesis that is observed with increasing age.

Y-autosome translocation interferes with meiotic sex inactivation and expression of autosomal genes: a case study in the pig.

Y-autosome translocations are rare in humans and pigs. In both species, these rearrangements can be responsible for meiotic arrest and subsequent infertility. Chromosome pairing abnormalities on the SSCX, SSCY and SSC1 chromatin domains were identified by analyzing pachytene spermatocytes from a boar carrying a (Y;1) translocation by immunolocalization of specific meiotic protein combined with FISH. Disturbance of the meiotic sex chromosome inactivation (MSCI) was observed by Cot-RNA-FISH and analysis of ZFY gene expression by sequential RNA- and DNA-FISH on spermatocytes. We hypothesized that the meiotic arrest observed in this boar might be due to the silencing of critical autosomal genes and/or the reactivation of some sex chromosome genes.

Translational regulation of the cell cycle: when, where, how and why?

Translational regulation contributes to the control of archetypal and specialized cell cycles, such as the meiotic and early embryonic cycles. Late meiosis and early embryogenesis unfold in the absence of transcription, so they particularly rely on translational repression and activation of stored maternal mRNAs. Here, we present examples of cell cycle regulators that are translationally controlled during different cell cycle and developmental transitions in model organisms ranging from yeast to mouse. Our focus also is on the RNA-binding proteins that affect cell cycle progression by recognizing special features in untranslated regions of mRNAs. Recent research highlights the significance of the cytoplasmic polyadenylation element-binding protein (CPEB). CPEB determines polyadenylation status, and consequently translational efficiency, of its target mRNAs in both transcriptionally active somatic cells as well as in transcriptionally silent mature Xenopus oocytes and early embryos. We discuss the role of CPEB in mediating the translational timing and in some cases spindle-localized translation of critical regulators of Xenopus oogenesis and early embryogenesis. We conclude by outlining potential directions and approaches that may provide further insights into the translational control of the cell cycle.

Ontogenesis of Ap-2γ expression in rat testes.

Searching for useful markers of spermatogonial stem cells and their differentiation, we used rat testes from ages representing different stages of testicular maturation to investigate the expression profile of transcription factor activation protein-2γ (Ap-2γ). The immunohistochemical and immunocytochemical evaluation using Ap-2γ and promyelocytic leukemia zinc finger in combination with sorting of CD9 and CD90 positive cells (undifferentiated spermatogonia) by fluorescence-activated cell sorting was performed. Our experiments revealed that Ap-2γ is detectable in testes of late fetal age and up to 60 days postnatally and is expressed in gonocytes and spermatogonia from late fetal age throughout all maturational stages. Restricted nuclear expression of Ap-2γ to undifferentiated male germ cells was verified by coexpression of Ap-2γ with promyelocytic leukemia zinc finger in sections of paraffin-embedded testes as well as in cells sorted positive for CD9 and CD90 expression. Our study demonstrated clearly that nuclear expression of Ap-2γ is a useful marker for identifying undifferentiated male germ cells, although its functional role is yet to be fully explored.

Galactosides in glycoconjugates of Xenopus laevis testis shown by lectin histochemistry.

The implication of galactosides and other glycoconjugates on spermatogenesis has been previously reported. Glycans show such a complex structure that it makes them very difficult to analyze. Lectin histochemistry is a helpful tool for the study of glycan composition. Lectin histochemistry can be combined with deglycosylation pretreatments to explore the glycan type to which carbohydrates are linked. The aim of the present work was the localization of galactose (Gal)-containing glycoconjugates in the testis of Xenopus laevis, a species widely used in cell, molecular and developmental biology. Gal specific lectins BPL, PNA, BSI-B4, MAA-I, and RCA-I, were used in combination with deglycosylation procedures. Except for BPL, all the lectins were reactive for several testicular tissues. Some of the lectins showed a different reactivity depending on the stage of spermatogenic development, suggesting that cell glycoconjugates are modified during spermatogenesis. The surface of primary spermatocytes was strongly labeled with lectins from peanut (PNA) and castor bean (RCA-I), which agrees with the presence of galactosyl-glycolipids reported in the cell membrane of mammalian spermatocytes. The acrosome was unexpectedly negative to all the lectins tested, whereas the acrosome of mammals and other amphibians has shown a high expression of glycoconjugates, including galactosides. The results obtained after deglycosylation by ß-elimination or incubation with PNGase F, which respectively remove O- and N-linked oligosaccharides, allowed us to elucidate the nature of the labeled glycans. The strong expression of galactosides at the cell surface of spermatocytes and spermatids suggests the involvement of these glycans in cell adhesion mechanisms during spermatogenesis.